Removal and Stabilization of Cadmium and Lead

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I have been using a magnesia-based product to remove Cd and Pb from industrial wastewater with a starting pH 6 to 8. The treated metals are chemically bound in the sediment and remain stable and suitable for landfill disposal or recycling. 

Since the product formula I have been using is no longer available, I am looking for a substitute product (dry powder) available in the US that will accomplish these objectives.

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7 Answers

  1. Keep in mind that I have three objectives; 1) to remove Cd and Pb ions from the wastewater, 2) to remove them in a form that is stable (refractory) so that the sediment will not release ions in the presence of acid during the TCLP test, and 3) to be able to use the without sophisticated or specialized equipment. In other words, I want to be able to use batch treatment regimen in any container or tank that is appropriate to the volume of water I wish to treat.  The product I am currently using does that.  Concentrations in the wastewater vary from 2 mg/L to 200 mg/L.  Target concentrations for the treated water are 0.02 mg/L or lower necessary to meet stringent local POTW discharge limits.

  3. I was wondering why you said "removed". If you were wanting to chelate the metal compounds into their elemental state then the RNA microbial group has been doing this for 3 billion years. Sold world wide.  I believe Pat had asked your limits.  If you would check with the International Institute of health and nutrition you will find both are nutrients needed for life. On an old chart I found 3 ppm of Cd is the level for ocean life. .6 ppm is the level for land based life. Pp. is .5 to 8.4 ppm for ocean life. 2,0 to 2.7 ppm for land based life.  Of course if you have an excess you will need to remove it.  But since ocean waters have a level of 13 ppm this would be a nutrient for ocean life.  Too many people misunderstood when told Heavy metals are toxic. They are not only a nutrient but are directly responsible for all immune systems in plant and animals.  If you eat one ice cream cone it is a nutrient/desert. If you try to eat one ton it become toxic to you.  Most waste treatment facilities are 50 years behind in science and technology.

  4. More information is always good if you are trying to get the right answer. What are your starting concentrations? What are your discharge limits? What is the volume or flow rate? What other compounds are in the water that could interfere? Normally Lead is precipitated as a hydroxide. Cadmium could be precipitated as either a hydroxide or as a sulfide. In order to get the right answer you will need to provide more information.

    1 Comment

    1. Keep in mind that I have three objectives; 1) to remove Cd and Pb ions from the wastewater, 2) to remove them in a form that is stable (refractory) so that the sediment will not release ions in the presence of acid during the TCLP test, and 3) to be able to use the without sophisticated or specialized equipment. In other words, I want to be able to use batch treatment regimen in any container or tank that is appropriate to the volume of water I wish to treat.  The product I am currently using does that.  Concentrations in the wastewater vary from 2 mg/L to 200 mg/L.  Target concentrations for the treated water are 0.02 mg/L or lower necessary to meet stringent local POTW discharge limits.

  6. New dewatering will solve the problem. 99.9% efficiency

    Need volume

    jim quigley

  7. Heavy metals are of special concern because of their persistence. Unlike organic contaminants, heavy metals are not biodegradable and tend to accumulate in living organisms. Furthermore, many heavy metal ions are known to be toxic or carcinogenic. Thus removal of these toxic heavy metals from wastewater is of crucial importance to protect the human population and the environment. Several heavy metals are particularly important in the treatment of industrial wastewaters i.e. zinc, copper, nickel, mercury, cadmium, lead and chromium Various methods exist for the removal of harmful metal ions, particularly heavy metals, from liquids and fluids e.g. waste waters. Chemical precipitation and coagulation-flocculation are the most widely used methods for removing pollutants. Often metals are removed from solutions by increasing the pH of the effluent, converting the soluble metal into an insoluble form (i.e. its hydroxide). Flotation, electrolytic reduction, ion exchange and membrane technologies are also widely used methods. Recently adsorption has been proposed as representing an alternative treatment procedure. Naturally occurring low cost adsorbent materials have been studied: e.g. agricultural waste, industrial by-products, clays, zeolites and chemically modified cellulose materials. In recent years, many alternative solid-phase sorbents (e.g. carbon nanotubes, fullerens, ion imprinted polymers, biosorbents, nanoparticles) have been investigated.

    To removing of Cu2+, Cd2+, and Pb2+ ions from solution and to investigate the adsorption isotherms, adsorption kinetics, and ion‐exchange affinities of these metals using waste activated sludge (AS) biomass. The adsorptions of the metals on biomass optimal at an acidic pH value of 6.0 based on its monolayer capacities. Maximum monolayer capacities of AS

    chemicals used (magnesium nitrate, urea, and ethanol) low cost and environmentally benign.

    Adsorption is known to be one of the best of the technologies for the decontamination of water because it is an effective, economical and ecofriendly treatment technique. It is a process strong enough to realize water reuse obligation and high runoff standards in the industries. Adsorption is basically a mass transfer process by which the metal ion is transferred from the solution to the surface of sorbent, and becomes bound by physical and/or chemical interactions . All adsorption bonding. Physical adsorption can only be occurred in the environment of low temperature and under appropriate pH conditions.

     

     

    1 Comment

    1. Most of your statement is true and very well laid out. May I clarify a few points that are correct but very misleading.  Line 2 mentions heavy metal ions are toxic. True. Only man makes metal compounds and thus loose ions.  Nature has the RNA microbes to fix mans mistake.  Even though your statement is true. You make it seem that all heavy metals are toxic and cause cancer. This is absolutely not true. Because of these false innuendos government agencies by law eliminate nutrients that are needed for all immune systems.  The reuse of all waters anywhere in the world is not a political football. All of the worlds water problems are caused by government agencies not doing their jobs.  This is nothing new. Bioremediation technology has been around at least 50 years. The monthly reports  continue to show ZERO pathogens and no toxic substances of any kind.

      You are spot on about plant absorption.  Though you do need to make it clear toxic metal compounds will also kill the plants. First deionize them using Archaea microbes. Then nature will do the rest. If excess maybe 2 or 3 years. Local County agents have a long list of which plant will absorb what metals.  Again nicely laid out.  All of this falls under the field of Bioremediation.  Any questions in that regard please feel free.

      1 Comment reply

      1. Ours is a filtration system to remove solids ti the micro level at a substantial rate per minute---100,000 gpm depending on contamination. Also desalination